of Vision ly Persons cured of Cataract . 209 



feet in ils function arises from continued inaction, and 

 'Can therefore only be cured by constant application. Those 

 "who possess the blessing of sight, are in the constant and 

 almost momentary habit of exercising the retina, while in a 

 congenital patient aW its powers are suffered to lie dormant. 

 Even in persons not born blind, who have successfully 

 undere;on« the operation for cataract, if the disease had 

 continued for many years, the functions of the retina 

 during this period have been much impaired, and are aflcr- 

 wards materially improved by exercise. If this partial 

 want of a natural sensibility in the retina be confined to 

 one eye, which is often the case in the slate-coloured ca- 

 taracts with transparent edges, the other eye should be 

 covered, or the spectacle before it obscured, to prevent the 

 passage of light, while the one afTccted is exercised as muchi 

 as possible. 



" In the hope of establishing a systematic plan of edu- 

 cating persons who have been unfortunately affected with 

 congenital cataracts, a young gentleman about 14 years 

 old, on whom I successfully performed the operation, has 

 been placed under the tuition of an able and ingenious 

 master, who has been made acquainted with the different 

 causes which appear to me to retard the acquirement of 

 vision, and with the means judged necessary to be em- 

 ployed in his instruction. The progress this patient made 

 while he was previously with his friends, by an attention 

 to some of these rules, leads me very sauguinely to anti- 

 cipate the greatest success from the present experiment. 

 After his recovery from the operation he could merely di- 

 stinguish colours, but was so entirely ignorant of the 

 forms of objects that he could not perceiVe any difference 

 between a square and a circle. To my great gratitication, 

 when he arrived in London, nine months after the operation, 

 he could read letters of a middle size, could help himself at 

 table without assistance, walk alone in the street, &c. ; and 

 I have great reason to hope, that at some future period I 

 •shall be able to lay before the public the favourable result 

 of my efforts, assi^d by those of the intellioent master ou 

 this intcrestmg subject. On the contrary, I have fre- 

 quently seen instances where the operation has been at- 

 tended with equal success ; yet, owing to a want of a pro- 

 per attention afterwards, the patient has derived little or no 

 benefit from it. A young lady upwards of twenty years 

 of age, one of the first persons I operated on at Exeter, to 

 whom I was enabled myself to pay at first a good deal of 

 •Itention, a n)oiith after she was cured, could distinguish 



Vv)l. 41. No. 179. iVfl/x/i 1813. the 



